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Dec. 7,1926. 1,610,177

W. M. STRONG DRIER Filed May 5, 1926. 2 Sheets-Sheet 1 IN V EN TOR.

A TTORNEYS.

Dec. 7 1926. 1,610,177

w. M. STRONG DRIER Filed May 5, 192 s 2 Sheets-Sheet 2 IN V EN TOR.

QQMM I ATTORNEYS.

Patented Dec. 7, 1926.

i T T T if.

WILLIAM M. STRONG, OF SANTA BARBARA, CALIFORNIA.

DRIER.

Application filed May 3, 1926.

This invention relates to improvements in the construction of forced circulation kilns or chambers for drying and conditioning lumber, fruit and similar materials.

The object of the present invention is to generally improve and simplify the construction and operation of driers; to provide a drier or kiln in which forced air circulation is obtained by a continuously driven, poweroperated fan and reversal of the air at predetermined time intervals by -adamper control; to provide a kiln or drier in which a maximum volume of air is continuously circulated over and over again and a predetermined humidity content maintained by condensing out excess moisture; to provide a kiln in which the internal air pressure is automatically maintained by means of equalizing air ducts, allowing excess moist air to escape with a corresponding inlet of fresh air 1; to provide a kiln capable of operation under any desired drying schedule based upon the adjustment and control of heat and humidity, with air as the circulating medium; to provide a kiln in which condensation of moisture when it does occur takes place below the drying chamber; to provide a kiln or drier in which equalized and uniform temperatures may be maintained throughout; and, further, to in sure a uniform product by uniform air distribution and by maintaining close humidity and temperature control.

The drier is shown by way of illustration in theaccompanying drawings, in which Fig. 1 is a central, vertical, longitudinal section through the drier.

Fig. 2 is a plan section, taken on the line a-2 of Fig. 1.

Fig. 3 is an end cross section taken on the line 33 of Fig. 1.

Referring to the drawings in detail, A andB indicate a pair of interspaced side walls carried by a floor or base section 0. The walls and floor sections are extended to any length desired and are covered by a roof section D, thereby producing a kiln or drier of considerable length when comparison is made with its width and height.

Disposed interiorly of the drier is an in termediate floor section 2 and a pair of interspaced walls 3 and 4 which extend from one end to within three or four feet of the front of the other end of the drier. These walls, together with the intermediate floor section, divide the drier into an upper dry- Serial' No. 106.229.

ing chamber E, a plenum chamber F and a pair of return air passages G and H. All the chambers and passages formed extend from end to end of the drier and their function and purpose will be hereinafter described. A trackway 5 extends through the drying chamber so that the material to be dried may be loaded on trucks and readily transported into and out of the drier. Each end of the drying chamber is, of course, provided with doors, such as shown at 6, which are open and closed as the trucks are moved into or out of the drying chamber.

The walls 3 and a forming the plenum chamber and the return air passages G and H extend from one end of the drier, as shown in Fig. 2, to the point indicated at 7. An end passage 8 is thus formed which communicates with the open end of the plenum chamber and with the respective return air passages G and H. A fan or blower 10 is mounted in the open end of the plenum chamber and the fan discharges the air in the direction of the arrow ainto the plenum chamber. Its suction side is presented to the passage 8 and air may thus be drawn from either of the return passages, as will hereinafter be described.

The fan may be driven in any suitable manner. for instance, by an electric motor, such as indicated at 11, and the air circulated by the fan is alternately heated and cooled when in circulation. Heating coils 12 are. mounted in the upper portion of the plenum chamber and they may be heated in any suitable manner, for instance, by the circulation of steam obtained from an exterior boiler or other suitable source of supply. Cooling of the air is ensured when the air passes through the return passages; this being accomplished by the conduction of heat to the side walls A and B by the admission of fresh air through dampers 25 and 26, and may further be assisted by water spray discharging from spray pipes such as shown at 14 and 15. The spray may also serve the purpose of washing out of the circulating air acid vapors from evaporation of the moisture, especially in redwood, preventing to a large extent corrosion of fan blades, housing and other metals within the kiln. Valves, such as indicated at 16, are employed to regulate the flow of cooling water.

Formed in the upper parts of the plenum chamber walls 3 and 4 is a series of interspaced air ducts 17 and 18, and cooperating y the arrmvs and will enter the end char;

with each set or ducts are dampers 19 and 20. The dampers 20 are all mounted on or controlled by one common shaft 21 extending through one side of the .lriln and provided with a lever whereby the shaft 1 be operated. Links 23 connect the dampers 1t) and 2t) and the connection is such that one set of dampers will assume an open pose tion 'WllEil the opposite get assumes a. closed position. This arrangement is oi partirular importance as it permits operation oi? the dampers in unison and, above all. permits reversal of the circulating air as will new be do: ibed.

In actual operation with the dampers a3- sun'iing the position shown in F 23, the air entering the plenum chamber and main-- tained in circulation by means of the tan it) will discharge through the ducts l8 and it will be deflected upwardly into the drying chamber as indicated by the arrows. (iratings or WztllS are arranged on each side ot the trackway 5 tor the convenience ot the workers, and they also serve another tune tion, lo-wit, that of evenly dietrilaiting the air discharging from the ducts 17.

It the trucks are loaded with, lumber, the

air will ass laterally through the sticker spaces of the stacks contained on the trucks and will then lie Y downvnu'dly on the opposite side of the "ruclts and return through the openings which communicate with the return duct H. The air will then flow longitudinally of this duct in the direction of 8 and the suction side oi the {an it to be circulated ov r and over again. The air, during it passage through the lumber. pi un amount oi moisture and in part precipitated out d v pa sage of the :1 through the retr...n hut H by conduction of heat to the side walls by water spray action. or by admitting mo'e less cool air through the dampers 25" and 26.

The floor section of the return duet-a slope as shown in Fig. 3, and gutters are formed in tie sides to CODES? and carry away the moi "ire condensed within the ltiln. The principal advantage of this arrz' enient is to prevent condensation of moistine in any part of tlr "W0 the t l r l air on enter the plenum chamber brought up to the required temperatme and it is accordin alternately h ate-d and cooled d1 ach cycle of recirculation.

By rel ing to Figs. 1 ant it will he noted that the upper dampers; 25" are pirotah ly mounted in passages 25" and similarly that the dampers 2c are sliding dampers and as such may be manually open or clor-ted.

The humidity content or the air circulating within the kiln previously stated is controlled by a steam yet- '27, and by conduction of heat to the side walls in the bottom ot into the kiln through the suction action 01? the fan. It is, oi? course, impossible to main tain an air pressure greater than atn1os-.:-- pheric pressure, and as fresh air enters a proportionate yolume oi moist air must be discharged. This is automatically taken care of by the swinging dampers 25*, as they are placed a greater distance from the suction side of the tan than the damper 26 and any slight pressure will cause them to swing outwardly and thereby permit a proportionate amount of moist air to discharge.

For edge stacked loading the design may be moditied by suitable arrangement oi? dampers.

During the operation lever 22 is grasped by the operator at suitable time intervals and rocked to reverse the position of the dampers 19 and 20. This reversal of the position or the dampers reverses the flow of air through the drying chan'iber and the lumber or other material dried is thus subjected to a uniform application of air. Practically any empcratrtc may be maintained by regulating the flow of steam through the heating coils and practically any humidity content array be maintained by opening or closing the humidity {team jet 2.

A tunnel type of drier is in reality employed, but the air flow is not longitudinally thereof as is common practice but conversely the air flow is transversely of the passage or tunnel at all points. It is accordingly impossible for the air to become moisture laden and to precipitate its moisture at points further ahead in the tunnel as is the usual result with ordinary types of tunnel driers. It for any reason it is decided to add moisture content to the circulating air a steam outlet is provided as shown at 27.

The general arrangement is such that a very fast and uniform circulation of air and vapor through the piles of lumber or other material in the proc of drying may be secured. T he arrangement permits periodic reversal oil? the direction of air movement by closing the dampers on one side ot': the plenum chamber and opening the dampers on the opposite side. The arrangementalso permits the use of a fan which continuously rotates in one direction. This is of articular importance as a curved blade isk fan of the mine ventilating type having almost double the etliciency of an ordinary flat blade disk tan and capable or operating against the resistance of one inch static pressure may be employed. The air distributing system provides a very uniform. tlow of air throughout the length and breadth of the kiln and eliminates non-uniformity of drying which is one 01? the commonest. troitibles experienced in the ordinary kiln.

lVhile certain -t'eatures ot the present invention are more or less specifically described and illustrated. I wish it understood that various changes may be resorted to within the scope of the appended claims. Also I wish it understood that the materials and finish of the several parts employed may be changed to suit varying conditions.

Having thus described my invention, what I claim and desire to secure by Letters Patent is 1. In a dry kiln having an elongated plenum chamber, a pair of return air passages and a superposed drying chamber, a plurality of air ducts on each side of the plenum chamber, and dampers cooperating with said ducts and adapted to place the ducts on opposite sides alternately in communication with the plenum chamber and the return passages.

2. In a dry kiln having an elongated plenum chamber, a pair of return air passages and a superposed drying chamber, a plurality of: air ducts on each side of the plenum chamber, dampers cooperating with said ducts and adapted to place the ducts on opposite sides alternately in communication with the plenum chamber and the return passages, and circulating means adapted to maintain a continuous circulation of air through the plenum chamber, the air ducts, the drying chamber and the return passages.

3. In a dry kiln having an elongated plenum chamber, a pair of return air passages and a superposed drying chamber, a plurality of air ducts on each side of the plenum chamber, dampers cooperating with said ducts and adapted to place the ducts on opposite sides alternately in communication with the plenum chamber and the return passages, circulating means adapted to maintain a continuous circulation of air through the plenum chamber, the air ducts, the drying chamber and the return passages, and means for reversing the dampers in unison to reverse the flow of air through the drying chamber.

4. In a dry kiln having an elongated plenum chamber, a. pair of return air passages and a superposed drying chamber, a plurality of air ducts on each side of the plenum chamber, dampers cooperating with said ducts and adapted to place the ducts on opposite sides alternately in communication with the plenum chamber and the return passages, and circulating means adapted to maintain a continuous circulation of air through the plenum chamber, the air ducts, the drying chamber and the return passages, and means for heating the air to a predetermined temperature.

5.111 a dry kiln having an elongated plenum chamber, a pair of return air passages and a superposed drying chamber, a plurality of air ducts on each side of the plenum chamber, dampers cooperating with said ducts and adapted to place the ducts on opposite sides alternately in communication with the plenum chamber and the return passages, circulating means'adapted to maintain a continuous circulation of air through the plenum chamber, the air ducts, the drying chamber and the return passages, and means for cooling the air during its travel through the return passages to condense moisture below the track level in the kiln.

6. In a dry kiln having an elongated plenum chamber, a pair of return air passages and a superposed drying chamber, a plurality of air ducts on each side of the plenum chamber, dampers cooperating with said ducts and adapted to place the ducts on opposite sides alternately in communication with the plenum chamber and the return passages. an air circulating tan in the plenum chamber, air heating means in the plenum chamber, means for regulating the temperature of said heating means and the air heated thereby, cooling means in the air return passages, and means for regulating the temperature of said cooling means and the air cooled thereby.

7. An apparatus of the character described comprising an elongated housing, a horizontal partition therein dividing the: housing into upper and lower compartments, said upper compartment being a drying compartment, a. pair of interspaced vertical partition members in the lower compartmentforming a central plenum chamber and apair of exterior air return passages, a plurality of air ducts arranged on each side of the horizontal partition member, dampers in said ducts adapted to place the ducts on one side in communication with the plenum chamber and the ducts on the other side in communication with one of the air passages or vice versa. means for reversing the position of the dampers in unison. and means for maintaining a continuous circulation of air through the plenum chamber, the ducts, the drying chamber and one or another of the return passages.

WILLIAM M. STRONG. 

